The researchers were careful to correct for other possible explanations, including weather, heat waves, precipitation, or more general, county-specific confounding factors."
https://www.sciencedaily.com/releases/2019/10/191003114007.h...
more activity -> more pollution -> more crime
more activity -> more crime
The paper's abstract says "The results suggest that a 10% reduction in daily PM2.5 and ozone could save $1.4 billion in crime costs per year, a previously overlooked cost associated with pollution." In my opinion this is a statement of a causal relationship, not merely a correlation.
I wonder why they didn't reverse that relationship, too, and propose that violent crime increases pollution.
I would love to read the actual paper, but it's only available to people with money.
Probably because you can easily rule out that possibility using common sense, whereas causation in the other direction is at least thinkable and worth investigating further.
Say what? You should write these scientists and explain, I'm sure they've never heard of this concept!